Reference voltages are used within the field of electronics in a large number of situations. They can be used for instance in a comparator to produce a known value against which another value can be compared.
Often in complex circuitry more than one voltage reference value is required. It is known in the art that a range of different value references can be created using circuitry as simple as a potential divider. A potential divider receives a first voltage and produces a second voltage or further voltages, the second or further voltages being a fraction of the first voltage dependent on the values of the potential divider network.
Furthermore, dependent on the components used in the voltage reference circuit each voltage reference has a temperature coefficient value which defines the change of the voltage reference value dependent on temperature. The temperature coefficient value may be positive, negative or zero. In other words the reference voltage value increases with, decreases with or is independent of the temperature.
Complex circuits can require a series of different voltage reference values each of which have a different voltage temperature coefficient.
In such a situation a circuit that generates a single voltage reference which is then divided using a potential divider cannot be used, as the voltage sources generated by such a circuit would have temperature characteristics divided in the same ratio as the potential divider voltage. Thus no one network could produce a range of voltage and temperature coefficient values other than those whereby the voltage and coefficient values were directly related.
Therefore there exists no single circuit whereby a series of voltage reference values with programmable voltage values and programmable temperature coefficients are provided, without the reference voltages being created individually.